For an economic activity input of 25 billion dollars1, the United States uses 760,000 TJ of energy on cotton farming2. Extrapolating from the fact that the United States produces roughly 16 percent of the world’s cotton3 and assuming relatively similar global farming practices, we can conclude that the United States figure represents roughly 1/6 of the total energy used in cotton production. This puts the global energy use for cotton production at nearly 4,500,000 TJ. While there certainly are small changes that could be made to increase efficiency and slightly lower the energy use, I’d like to take a look at another figure to put 4,500,000 TJ into perspective.
In order to put this number in a more familiar context, I’ll compare it to the aluminum industry, which we’ve been studying as one of the largest energy consumers. Although the textbook has some data for energy use in aluminum production, I opted to perform a calculation using the same method in which I calculated cottons energy use, so that the numbers would be comparable. For an economic activity input of 152 billion dollars4, the United States uses 7,450,000 TJ of energy2. This number only accounts for the energy used in primary production, and it’s an order of magnitude greater than the energy used in cotton production in the United States. An important concept discussed in the textbook is that of scale5. I think that cotton production has a small enough impact compared to other industries that increasing the efficiency would do little to decrease total energy consumption.
Although making cotton production more efficient would have little effect on overall energy consumption, there are a couple of small changes that could be done to slightly decrease energy use. Cotton recycling is difficult because breaking down fabric results in shorter fibers than the original cotton production, and those fibers are difficult to spin into new products. Also, the energy associated with transporting, sorting, breaking down and re-dying cotton can be very large.6 However, consumers can decrease their cotton demand by reusing cotton; rather than buying new clothes, buy secondhand; rather than buying hand towels or cleaning rags, use old shirts.
A primary area of concern with cotton production is the use of pesticides and fertilizers. While cotton may not be a huge contributor in terms of energy, it accounts for 25 percent of the chemical pesticides used in the United States7, and probably even more in under regulated parts of the world. While energy production releases a lot of greenhouse gases, I think that the unknown effects of pesticides and fertilizers could be much more damaging in the long run than the carbon releases associated with energy use. Below is a graph showing the amount of toxic releases from cotton farming in the United States:
While ‘organic chemical manufacturing’ sounds benign, it actually includes many pesticides that can wreak havoc on local ecosystems and lead to the development of superweeds and other pests that pose a serious threat to future agriculture. Although it would be less energy efficient (which kind of goes against the topic of this post), I think that the cotton industry should start to switch over to bamboo or organic cotton.